Import //fetch from Web Platform Tests.

third_party/WebKit/LayoutTests/external/wpt/fetch/http-cache/resources/http-cache.py

+from json import JSONEncoder, JSONDecoder
+from base64 import b64decode
+
+def main(request, response):
+    uuid = request.GET.first("token", None)
+    if "querystate" in request.GET:
+        response.headers.set("Content-Type", "text/plain")
+        return JSONEncoder().encode(request.server.stash.take(uuid))
+
+    server_state = request.server.stash.take(uuid)
+    if not server_state:
+        server_state = []
+
+    requests = JSONDecoder().decode(b64decode(request.GET.first("info", "")))
+    config = requests[len(server_state)]
+
+    state = dict()
+    state["request_method"] = request.method
+    state["request_headers"] = dict([[h.lower(), request.headers[h]] for h in request.headers])
+    server_state.append(state)
+    request.server.stash.put(uuid, server_state)
+
+    note_headers = ['content-type', 'access-control-allow-origin', 'last-modified', 'etag']
+    noted_headers = {}
+    for header in config.get('response_headers', []):
+        if header[0].lower() in ["location", "content-location"]: # magic!
+            header[1] = "%s&target=%s" % (request.url, header[1])
+        response.headers.set(header[0], header[1])
+        if header[0].lower() in note_headers:
+            noted_headers[header[0].lower()] = header[1]
+
+    if "access-control-allow-origin" not in noted_headers:
+        response.headers.set("Access-Control-Allow-Origin", "*");
+    if "content-type" not in noted_headers:
+        response.headers.set("Content-Type", "text/plain")
+    response.headers.set("Server-Request-Count", len(server_state))
+
+    code, phrase = config.get("response_status", [200, "OK"])
+
+    if request.headers.get("If-Modified-Since", False) == noted_headers.get('last-modified', True):
+        code, phrase = [304, "Not Modified"]
+    if request.headers.get("If-None-Match", False) == noted_headers.get('etag', True):
+        code, phrase = [304, "Not Modified"]
+
+    response.status = (code, phrase)
+
+    content = config.get("response_body", uuid)
+    if code in [204, 304]:
+        return ""
+    else:
+        return content